title: CT angiography for pulmonary embolism detection: the effect of breathing on pulmonary artery enhancement using a 64-row detector system.
abstract: BACKGROUND
  Computed tomography pulmonary angiography (CTPA) is used most often in routine clinical practice for the assessment of a suspected pulmonary embolism. The diagnostic accuracy relies on sufficient contrast enhancement.
  
  
  OBJECTIVE
  To evaluate whether image acquisition during shallow breathing can improve the image quality in patients with insufficient contrast enhancement during breath-hold examinations.
  
  
  METHODS
  A total of 2786 CT pulmonary angiographies, acquired on a 64-row CT during deep-inspiration breath-hold, were reviewed. Twenty-four examinations were considered non-diagnostic due to poor contrast enhancement in the pulmonary arteries (PA), although they showed preserved vascular enhancement of the superior vena cava (SVC) and the ascending aorta (AO). Eleven flawed CTPA examinations, including severe breathing artifacts and incorrect triggering were excluded. In 13 of the remaining patients, the examination was repeated during shallow breathing. Vascular contrast enhancement was compared between both scans by measuring the relative enhancement within the SVC, the main PA, and the AO. Image quality was scored by two, clinically experienced radiologists. The values are given as median and [25th;75th] quartile.
  
  
  RESULTS
  There was a significant difference in the CT values for the PA between the repeated scans (P = 0.0002, Wilcoxon test), and with the CTPA in deep-inspiration showing a median enhancement of 97 HU (59-173), compared with 303 HU (239-385) in the CTPA acquired during free breathing. The differences for both the AO (P = 0.54) and the SVC (P = 0.78) were not significant. Scoring for the attenuation quality rose significantly (P = 0.0002) and no severe motion artifacts were detected on either scans.
  
  
  CONCLUSIONS
  If there is insufficient pulmonary artery enhancement during CTPA, attenuation of the pulmonary arteries can be improved by acquisition during shallow breathing and is without significant loss of the overall diagnostic image quality.
authors.affiliation: Department of Diagnostic and Interventional Radiology, Hannover Medical School, Hannover, Germany renne.julius@mh-hannover.de.
authors.forename: Julius
authors.initials: J
authors.lastname: Renne
authors.affiliation: Department of Diagnostic and Interventional Radiology, Hannover Medical School, Hannover, Germany.
authors.forename: Christian von
authors.initials: Cv
authors.lastname: Falck
authors.affiliation: Department of Diagnostic and Interventional Radiology, Hannover Medical School, Hannover, Germany.
authors.forename: Kristina Imeen
authors.initials: KI
authors.lastname: Ringe
authors.affiliation: Department of Diagnostic and Interventional Radiology, Hannover Medical School, Hannover, Germany.
authors.forename: Hans-Jürgen
authors.initials: HJ
authors.lastname: Raatschen
authors.affiliation: Department of Diagnostic and Interventional Radiology, Hannover Medical School, Hannover, Germany.
authors.forename: Frank
authors.initials: F
authors.lastname: Wacker
authors.affiliation: Department of Diagnostic and Interventional Radiology, Hannover Medical School, Hannover, Germany.
authors.forename: Hoen-Oh
authors.initials: HO
authors.lastname: Shin
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016477:Artifacts; D002648:Child; D002675:Child, Preschool; D003287:Contrast Media; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007479:Iopamidol / Q000031:analogs & derivatives; D008297:Male; D008875:Middle Aged; D061330:Multidetector Computed Tomography / Q000379:methods*; D011651:Pulmonary Artery / Q000000981:diagnostic imaging*; D011655:Pulmonary Embolism / Q000000981:diagnostic imaging*; D011856:Radiographic Image Enhancement / Q000379:methods*; D015203:Reproducibility of Results; D012119:Respiration; D012189:Retrospective Studies; D055815:Young Adult
chemical_list: D003287:Contrast Media; C057937:iomeprol; D007479:Iopamidol
keywords: Multidetector computed tomography; angiography; pulmonary embolism